Check out some similar questions!

JoshuaMB · Dec 11, 2006, 06:38 PM

Hi. I need to replace an upstairs sink hot water valve to a sink. I found and turned off the water to the house on the outside of the house. It did turn down the water pressure but never shut the water off completely, and all the household faucets would still provide both hot and cold water...
Is the outside valve not shutting all the way? I was advised not to crank it open or closed too forcefully or it might break, so I didn't close it tight- could it still be open enough to provide water thruout the house?
Do I need to drain the hot water heater if I want to work on the hot water side of the pipes?
I am trying to replace the sink hot water valve because it is a one piece design with the hose to the sink pressed on to the currrent valve- I want to install a normal valve and separate hose to sink so that I can install a Y splitter to feed a Bidet off the hot water side of the sink- the cold water side has a normal valve that allows it to have a Y connector installed on the other side of the valve to feed the bidet cold water.
It is an add on bidet and connects to the toilet seat itself.
Thank you!

Morrowrj · Dec 11, 2006, 06:54 PM

I would be careful turning an outside main, deending on age it could break easily. Did you check your hot water tank for inlet/outlet valves ?

labman · Dec 11, 2006, 07:32 PM

You don't need to drain the hot water tank, only make sure water is free to flow in and out either the inlet or outlet. Normally that is taken care of by the inlet, but will not be if you manage to shut the main valve off. If you have a stop under the sink, or a shut off on the hot water tank, you can leave the main valve on, allowing water to flow in and out of it, and shut the hot water off after the tank just as in normal use. If you have to shut off the main valve which doesn't sound like will work, or a valve on the inlet, then turn the gas to pilot or shut the electricity off to the tank. Leave a hot water tap open somewhere so water can flow in and out of the tank.

When you are done, close the hot water tap you left open, and immediately open the cold water you shut off. Open a hot water tap to allow any air that worked its way in out again. When the tank is full and has the cold water line open, turn the gas or electricity back on. Remember, either the inlet or the outlet and a tap must be open at all times. Water expands and contracts with temperature changes. It has to go somewhere.

JoshuaMB · Dec 11, 2006, 07:40 PM

Thank you for your answers...
Is it possible that I did not turn off the main line valve tight enough?
I was warned against over doing it so I may have not done it tight enough as a result.
If I shut off the main line, all water should stop (or slow to only a residual trickle) at all faucets, both hot and cold, right?
I was confused as to whether shutting off the main line would also stop the hot water left in the hot water heater... It will- correct?

speedball1 · Dec 12, 2006, 11:23 AM

Shutting off the house shut off shuts down everything. Regards, Tom

eagleflite1 · Jul 20, 2012, 09:43 PM

I drained my hot water tank and disconnected the supply line but water is still flowing from a hot water valve near the tank. What's causing this?

massplumber2008 · Jul 21, 2012, 06:50 AM

Hi Eagleflite1

The issue could be a cross over connection such as a single lever faucet/valve allowing some cold water to cross back over into your hot water supply. Culprits famous for this are any single handle faucets, shower valves, and washing machine valves. You could also have an expansion issue here, but I doubt that right now.

To get you moving again, you may need to shut off the cold main water supply to your home... should stop flow after you drain everything. Be careful of touching the main water supply if it is super old... sometimes they won't turn back on... ;)

You can try to isolate the cross over connection later if you want.

Mark